CIP-0133: Add BLS12-381 multi scalar

[perturbing]

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[perturbing]

@kwxm when costing, we should run the bench against different thresholds here. This 10 is an arbitrary value I randomly picked, I remember from the initial rust benchmarking @dkaidalov did, this threshold was 30, but I am unsure. Do you remember Dmytro?

[dkaidalov]

not sure what threshold do you mean? From my benchmarks the blst MSM is more efficient than naive impl already from the size of 3. There is indeed a threshold at 30, when the blst lib becomes suddenly several times more efficient (if I remember correctly there is some MSM mechanism switching at 30, programmed in rust bindings)